Adding Link to Solidity ERC20 Standard Article

Hey!

I was trying to utilize the Solidity Methods and Events, however, there wasn't further documentation. I found the attached Alchemy link to be extremely useful as it directly enhanced my understanding of this article and understand the functionality of specific methods and events. The link also linked the methods to some useful deployment data structures in Solidity, allowing me to use the functions more easily.

Author: vardhanshorewala

src/content/developers/docs/standards/tokens/erc-20/index.md

@@ -151,5 +151,6 @@ print("Addr Balance:", addr_balance)
 ## Further reading {#further-reading}
 
 - [EIP-20: ERC-20 Token Standard](https://eips.ethereum.org/EIPS/eip-20)
+- [Guide to Solidity ERC20 Tokens](https://www.alchemy.com/overviews/erc20-solidity)
 - [OpenZeppelin - Tokens](https://docs.openzeppelin.com/contracts/3.x/tokens#ERC20)
 - [OpenZeppelin - ERC-20 Implementation](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol)